Write the following using literals, numbers, and signs of basic operations: $y$ decreased by $7$.

Write the given statement using literals, numbers and signs of basic operations:

The difference of $a$ and $b,$ when $a>b$

Write the algebraic expression for, $x$$y$ added to their sum.

Write the following using literals, numbers, and signs of basic operation.

One-third of $x$ multiplied by the sum of $a$ and $b$ is $\frac{1}{3}x\left(k\right)$, then $k$ is $\left(a+b / a-b / ab\right)$

Write the algebraic expression for, $5$ times $x$ added to $7$ times $y$.

Sum of $x$ and the quotient of $y$ by $5$ is $a+\frac{k}{b}$. Find the value of $k$.

Write the algebraic expression for, $x$ taken away from $4$.

Write the following using literals, numbers, and signs of basic operations:

$2$ less than the quotient of $x$ by $y$

Writing the algebraic expression for, $x$ multiplied by itself, we get, $x^k$. Find $k$.